Enable HTML5 YouTube playback on Firefox

Today we will learn how to enable HTML5 YouTube playback on Firefox, since it is supported by version 36 of the popular Mozilla browser.
HTML5 is a markup language used for structuring and presenting content for the Internet introduced by World Wide Web Consortium (W3C). The HTML5 specification introduced the video element for the purpose of playing videos, partially replacing the object element and without the support of plugins, like the proprietary Adobe Flash plugin.

To enable HTML5 YouTube playback on Firefox, open the custom setting page:
Search the following key:
And set it to “True“.
Restart Mozilla Firefox and now you can have HTLM support for YouTube playback.